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  • 1.
    Ahmadi-Naghadeh, Reza
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering and Lighting Science.
    Liu, Tingfa
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Vinck, Ken
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Jardine, Richard J.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Kontoe, Stavroula
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Byrne, Byron W.
    Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
    McAdam, Ross A.
    Department of Engineering Science, University of Oxford, Oxford, United Kingdom.
    A laboratory characterisation of the response of intact chalk to cyclic loading2022In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656Article in journal (Refereed)
    Abstract [en]

    This paper reports the cyclic behaviour of chalk, which has yet to be studied comprehensively. Multiple undrained high-resolution cyclic triaxial experiments on low-to-medium density intact chalk, along with index and monotonic reference tests, define the conditions under which either thousands of cycles could be applied without any deleterious effect, or failure can be provoked under specified numbers of cycles. Intact chalk’s response is shown to differ from that of most saturated soils tested under comparable conditions. While chalk can be reduced to putty by severe two-way displacement-controlled cycling, its behaviour proved stable and nearly linear visco-elastic over much of the one-way, stress controlled, loading space examined, with stiffness improving over thousands of cycles, without loss of undrained shear strength. However, in cases where cyclic failure occurred, the specimens showed little sign of cyclic damage before cracking and movements on discontinuities lead to sharp pore pressure reductions, non-uniform displacements and the onset of brittle collapse. Chalk’s behaviour resembles the fatigue response of metals, concretes and rocks, where micro-shearing or cracking initiates on imperfections that generate stress concentrations; the experiments identify the key features that must be captured in any representative cyclic loading model.

  • 2.
    Ahmadi-Naghadeh, Reza
    et al.
    Architecture and Civil Engineering Department, Chalmers University of Technology, Gothenburg, Sweden.
    Toker, Nabi Kartal
    Civil Engineering Department, Middle East Technica University, Ankara, Turkey.
    A new isotropic specimen preparation method from slurry for both saturated and unsaturated triaxial testing of a low-plasticity silt2019In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 42, no 4, p. 854-879Article in journal (Refereed)
    Abstract [en]

    A new procedure for the preparation of low-plasticity silt specimens that are isotropically reconstituted from slurry is developed for use in both saturated and unsaturated soil testing. Spatial variations of the water content and grain size distribution were examined to confirm the uniformity of the specimens (regarding void radio and segregation). The new preparation method results in a homogeneous specimen, which has a simple stress history. The repeatability of the proposed method in preparing identical specimens was verified for both saturated and unsaturated soil testing. The strength and volumetric behavior of specimens prepared by the introduced method are compared with those of moist-tamped compacted specimens and one-dimensionally reconstituted slurry specimens by performing consolidated drained triaxial tests. The microstructure of the specimens prepared with different methods was examined using Scanning Electron Microscopy and Mercury Intrusion Porosimetry. The test results indicate that silt specimens could exhibit either dilative or contractive behavior at normal consolidated conditions, depending on the microstructure.

  • 3.
    Ahmadi-Naghadeh, Reza
    et al.
    Architecture and Civil Engineering Department, Chalmers University of Technology, Gothenburg, Sweden.
    Toker, Nabi Kartal
    Civil Engineering Department, Middle East Technical University, Ankara, Turkey.
    Exponential Equation for Predicting Shear Strength Envelope of Unsaturated Soils2019In: International Journal of Geomechanics, ISSN 1532-3641, E-ISSN 1943-5622, Vol. 19, no 7, article id 04019061Article in journal (Refereed)
    Abstract [en]

    An exponential equation is introduced to predict the nonlinear variation of shear strength with matric suction for unsaturated soils. The proposed equation involves three constant parameters, two of which are effective shear strength parameters (i.e., ′ and c′). The third parameter is the maximum capillary cohesion, c″max, which is the maximum possible increase in shear strength due to matric suction. A procedure for the determination of c″max from the soil-water characteristic curve (SWCC) is devised. The proposed equation is validated through a series of constant-suction consolidated drained triaxial tests conducted on specimens reconstituted by isotropic consolidation from the slurry state. In addition, the validity of the equation is investigated by applying it to the test results of five other soils that were available in the literature for the low-suction range (i.e., up to 1,500 kPa). A comparative study on the prediction of shear strength was carried out between the proposed equation and six other shear strength equations found in the literature. The results show that the proposed equation provides reliable predictions of the shear strength of unsaturated soils when the shear strength converges to an asymptotic value at the residual water content.

  • 4.
    Ahmadi-Naghadeh, Reza
    et al.
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Toker, Nabi Kartal
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Volume change measurement in triaxial testing of unsaturated soils2012Conference paper (Refereed)
  • 5.
    Ahmadi-Naghadeh, Reza
    et al.
    Civil Engineering Department, Istanbul Aydin University, Küçükcekmece/istanbul, Turkey.
    Toker, Nabi Kartal
    Civil Engineering Department, Middle East Technical University, Cankaya/Ankara, Turkey.
    Volume change measurement in triaxial tests by monitoring cell fluid volume based on viscoelastic behavior of the test setup2017In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 40, no 4, p. 683-697Article in journal (Refereed)
    Abstract [en]

    A novel procedure was developed to measure the total volume change of the unsaturated soils in triaxial testing. The principle of the proposed method was based on cell fluid volume measurements corrected by the assumption of viscoelastic behavior for the triaxial setup. Calibration and parameter determination procedures of the model are devised, and the presented model is implemented into a MATLAB code. The proposed method was validated through a series of consolidated drained triaxial tests on saturated specimens, by comparing the changes in volume measurement of proposed method and conventional measurement (pore fluid). The accuracy in volume measurement during consolidation and shear stages of these tests was between 0.09 and 0.32 cm3, which is on par with or better than more complex and expensive alternatives found in the literature. Repeatability of the proposed technique in measurement of the volume change was also investigated through a series of suction controlled unsaturated soil tests.

  • 6.
    Ahmadi-Naghadeh, Reza
    et al.
    Department of Civil Engineering, METU, Ankara, Turkey.
    Toker, Nabi Kartal
    Department of Civil Engineering, METU, Ankara, Turkey.
    Ahmadi-Adli, Mohammad
    Department of Civil Engineering, METU, Ankara, Turkey.
    Water content controlled instead of suction controlled strength tests2013In: Life Science Journal, ISSN 1097-8135, Vol. 10, no 1, p. 2023-2030Article in journal (Refereed)
    Abstract [en]

    Most soils that concern geotechnical engineering are in the state of partial water saturation. Current practice tries to predict engineering properties of cohesionless soils using data from tests on saturated specimens, regardless of the saturation in the field. Due to complexity of test setups and high technical requirements, unsaturated soil tests are not among the common equipment of soil mechanics laboratory. One of these problems is the existence of suction, which is a function of water content and affects the strength behavior of unsaturated soils. Procedures to keep the water content of the partially saturated specimens constant and homogeneous in conventional soil tests are not well-established. The exception to this is unsaturated test setups, which are costly, complicated and found only in research institutions, hence prohibiting the industry from keeping up with the developments in this field. This study explores simple modifications to conventional methodologies of triaxial and direct shear tests, with the ultimate aim of preventing temporal and spatial variability of specimen water content throughout test duration. For different modifications, specimens of each test are dissected at the end of the test, and water content profiles of the specimens are obtained.

  • 7.
    Ahmadi-Naghadeh, Reza
    et al.
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Toker, Nabi Kartal
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Ahmadi-Adli, Mohammad
    Department of Civil Engineering, METU, Ankara, Turkey.
    Water content variability of unsaturated soil specimens in conventional strength tests2012Conference paper (Refereed)
  • 8.
    Al Masalmeh, Omar
    et al.
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Al Kass Youssef, Daoud
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    En numerisk analys av olika scenarier som påverkar släntstabiliteten för en del av projekt Lappen 19 i Munksjöstaden2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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  • 9.
    Ali, Rebaz
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineeering and Lighting Science.
    Alshami, Ahmed
    Jönköping University, School of Engineering, JTH, Civil Engineeering and Lighting Science.
    Sättningar i torvmaterialet: En fallstudie om användning av förstärkningsmetoden "förbelastning i form av överlast" på jordmaterial av torv2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose: The aim of this degree project is to control the set-up for a longer period by means of the workplace at the use of the total station for then comparing calculated outcomes with real outcomes.

    Method: A combination of both quantitative and qualitative studies have been used in this degree project, consisting of literature studies and a case study including interviews, document analyzes, site visits and measurements. The case study is based on an ongoing project in the municipality of Nassjo, where a skate park is constructed and whose soil consists of peat. Preload in the form of overload has been applied.

    Findings: The result indicates the occurrence of a difference between calculated outcome and actual outcome regarding set rate and time course when using preload in the form of overload. The deviation is about 20 cm. Preload in the form of overload is a good method for peat land, but it is unlikely to be remarkably improved by vertical drainage.

    Implications: In view of the measurements produced by the authors, this shows that the method of loading in the form of overload on peat field works, however, gives the calculation model which has been used to be uncertain. The result described in more detail regarding vertical drainage on peat fields will not accelerate the process because the peat is already well drained. This means that it will cost extra without benefiting from the method.

    Limitations: The work has limited to two reinforcement methods on peat fields. A case study has been limited to only one area. There was preload in the form of overload, whose soil material consists of peat.

    Keywords: Peat, Permeability, Preloading in the form of overload, settlements, total station, vertical drainage, water quota.

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    Sättningar i torvmaterialet
  • 10.
    Birmpilis, Giorgios
    et al.
    Division of Geology and Geotechnics, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Ahmadi-Naghadeh, Reza
    Division of Geology and Geotechnics, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Dijkstra, Jelke
    Division of Geology and Geotechnics, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Macroscopic interpretation of nano-scale scattering data in clay2019In: Geotechnique Letters, E-ISSN 2045-2543, Vol. 9, no 4, p. 355-360Article in journal (Refereed)
    Abstract [en]

    The potential of X-ray scattering measurements for monitoring changes on the nano-scale in fine-grained materials in their natural wet state is demonstrated with a series of feasibility tests on well-controlled kaolin samples - that is, water content, pH and loading history. The results indicate that subtle changes on the nanometric scale, especially the particle orientations, can be measured with high fidelity using a standard laboratory small- and wide-angle X-ray scattering instrument. This opens up possibilities for future in situ loading tests with simultaneous monitoring of the evolving changes of the fabric in fine-grained soils.

  • 11.
    Birmpilis, Giorgios
    et al.
    Chalmers University of Technology, Department of Architecture and Civil Engineering, Gothenburg, Sweden.
    Ahmadi-Naghadeh, Reza
    Chalmers University of Technology, Department of Architecture and Civil Engineering, Gothenburg, Sweden.
    Dijkstra, Jelke
    Chalmers University of Technology, Department of Architecture and Civil Engineering, Gothenburg, Sweden.
    Towards a methodology for the characterisation of the fabric of wet clays using x-ray scattering2019Conference paper (Refereed)
    Abstract [en]

    X-ray scattering is a promising non-invasive technique to study evolving nano- and micro-mechanics in clays. This study discusses the experimental considerations and a successful method to enable X-ray scattering to study clay samples at two extreme stages of consolidation. It is shown that the proposed sample environment comprising flat capillaries with a hydrophobic coating can be used for a wide range of voids ratios ranging from a clay suspension to consolidated clay samples, that are cut from larger specimens of reconstituted or natural clay. The initial X-ray scattering results using a laboratory instrument indicate that valuable information on, in principal evolving, clay fabric can be measured. Features such as characteristic distance between structural units and particle orientations are obtained for a slurry and a consolidated sample of kaolinite. Combined with other promising measurement techniques from Materials Science the proposed method will help advance the contemporary understanding on the behaviour of dense colloidal systems of clay, as it does not require detrimental sample preparation. 

  • 12.
    Göransson, Martin
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering and Lighting Science.
    Brodnäs, Philip
    Jönköping University, School of Engineering, JTH, Civil Engineering and Lighting Science.
    Kvalitetssäkring av packning med digitala verktyget MCA-30002021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose: Compaction is one of the fundamental pillars of construction, without a proper compaction of ground material deformation may occur shorty after completed construction. A flaw of the traditional method of compaction control is that only point sources are obtained. This means that you can easily miss weak points of the compaction. This becomes significant when dealing with compaction of larger areas. The purpose of this study is to investigate how digital technology can ensure the compaction quality compared to traditional methods, and to expand the company’s knowledge of the application of the compaction computer MCA-3000.

    Method: The method chosen to gather data for this study were literature study, case study and interviews.

    Findings: The findings show how the compaction computer can be used to ensure compaction quality. An important factor is to know the conditions of the ground material in order to ensure a credible result. The case study suggest that the compaction computer can be used to visually show the compaction quality of an area. However, I cannot be used as a separated method to ensure compaction quality. The compaction computer needs test surfaces to be calibrated with assistance of traditional methods. This means that it cannot replace the traditional method. However, it can be used as a complementary tool to support the traditional methods. In the interviews, both the respondents pointed out that the compaction computer cannot be used as a separate method but can be used as a complementary tool for the contractors. 

    Implications: Our conclusions are as followed:

    ·         The compaction computer cannot be used as a single method to ensure compaction quality.

    ·         The compaction computer implies that it can be used as a complementary tool to support the traditional methods to ensure compaction quality of lager areas. 

    ·         The compaction computer allows the user to detect faults in real time during the compaction prosses.

    Our results indicate that the compaction computer can be uses as a complementary tool to support the traditional methods but not as its own method. To ensure the reliability of the compaction computer MCA-3000 further studies needs to be conducted to see how it preform with different ground material condition. 

    Limitations: Our result was limited by access of data. We were only able to collet data from a single project in a relatively small area, this means we only were able to get three data sources of compaction quality conducted with a tradition method. Another limitation was that the entire area had the same ground condition which means the result is only applicable in our case. 

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  • 13.
    Johansson, Alexander
    et al.
    Jönköping University, School of Engineering.
    Hallgren, Herman
    Jönköping University, School of Engineering.
    Utredning och test av olika jordtryckskoefficienter med hänsyn till fraktionsstorlekar på stödkonstruktioner2022Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduction – A question has been raised regarding how earth pressure is being calculated regarding classical textbook theory, the Swedish Transport Administration and Eurocode by the company Vara byggkonsult AB. To create a better understanding of the subject a practical test is being derived from classical theories and compared to these.Method – The chosen research method is a litterature study and an experimental quantitative test. To produce a test an iterative process is being used that is beeing updated according to observations and discussions.Results – Calculated values for the active earth pressure coefficient with the different methods vary between 0,221 – 0,278 for the material 0-4 and between 0,25 – 0,334 for the material 8-16 depending on which method is used. For the measured values, these vary from 0,173 – 0,279 for the material 0-4 and 0,227 – 0,296 for the material 8-16, depending on the load added. The fact that the values vary depends on factors such as internal friction angle, friction between the supporting wall and material, calculation method and which load was used when the test was carries out.Analysis – By comparing the calculation methods with the measured test values, it is possible to see similarities and differences between the results. For the material 0-4, it is possible to see a similarity between the calculated values for the calculation methods where the friction is assumed to be 0. For the material 8-16, the measured value is constantly lower than the calculated values for all calculation methods. For both material types, a trend can be seen where the increase in the measured value decreases the higher the load that is applied. An analysis based on question two has been done where the model and method for preforming the practical test has been analysed. The results produced from the model are credible and are repeatable to a high degree. The model has been constructed with materials and tools available in a regular hardware store. Material list and drawing of the construction have been documented and that the method for carrying out the tests is well documented.Based on an analysis of the effect of fraction size on the measured pressure, it is observed that a fine-grained material such as 0–4 can achieve a higher pressure than a coarser material such as 8–16. The tests carried out support this as material 0–4 results in a higher earth pressure coefficient than material 8–16. However, this is contradictory to how, classically speaking, there is an increase in friction angle the larger the fraction size is.Discussion – The Swedish Transport Administration's method of calculating the earth pressure coefficient is considered easier to use in comparison to Eruocde's method, as no more than an estimation of the material's properties is required.Factors such as the human factor is something that is also addressed in the report that has had an impact on the final result as well as the execution of tests. Drawing up a model digitally with perfect lines is one thing, but building it in real life is another. To counteract factors such as the human factor, a number of different changes have been made to the model and the execution of the tests.According to the results produced, it appears that there is a difference between the different materials, but this is not a big difference. The friction angles of the materials iido not differ by many degrees and therefore a large force difference has not been measured either.As the basic knowledge at the start of the survey was not particularly high, it led to mistakes that could have been avoided. The time spent on fixing those mistakes could instead be spent on improving the model to get even better values.

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  • 14.
    Jönsson, Clara
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Larsson, Linn
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Kartläggning av kvicklera med hjälp av flygresistivitetsmätningar2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Purpose: One of the major soil problems that the construction industry may face is the presence of a certain type of highly sensitive marine clay, known as quick clay. The quick clay possesses properties that allow the clay to move from being relatively stable to on mechanical impact losing virtually all shear strength and act as a viscous mass. The majority of the Swedish, Norwegian and Canadian landslides, caused by quick clay, have caused significant consequences due to lack of bearing capacity of quick clay. In order to prevent these landslides knowledge about where there is quick clay is required. A large-scale mapping work has therefore been ongoing for a long time. The government has for some time been researching how to streamline mapping work and the result has shown a connection between quick clay attendance and increased resistivity. The purpose of this study is to develop a theoretical framework for areas with higher risk for presence of quick clay based on linking the resistivity to geotechnical properties.

    Method: The study has mainly applied quantitative data collection methods in the form of data analyzes combined with literature studies. Measurement data used in the study comprise of data collected through geotechnical and geophysical surveys. Literature studies have mainly been supported by reports from previous research in the field. Result: The result of the study points to a variety of geological factors that can give rise to increased risk of quick clay existence such as good permeability, artesian groundwater and uneven mountain subsidence etc. The study also shows a possible link between resistivity and sensitivity.

    Consequences: The study demonstrates the possibility of linking resistivity to the geotechnical property sensitivity to facilitate and streamline the mapping of quick clay through airborne resistivity measuring.

    Limitations: The study is limited to studying two research areas in south western Sweden, Strömstad and Lödöse. The study intends to examine the evidence from previous surveys and no further supplementary studies are conducted. The work is also delimited to study the geotechnical and geophysical properties of quick clay (in terms of resistivity). Chemical aspects are not taken into account.

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  • 15.
    Liu, Tingfa
    et al.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Ahmadi-Naghadeh, Reza
    Jönköping University, School of Engineering, JTH, Civil Engineering and Lighting Science.
    Vinck, Ken
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Jardine, Richard J.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Kontoe, Stavroula
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Buckley, Róisín M.
    School of Engineering, University of Glasgow, Glasgow, United Kingdom.
    Byrne, Byron W.
    Department of Engineering Science, Oxford University, Oxford, United Kingdom.
    An experimental investigation into the behaviour of de-structured chalk under cyclic loading2022In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656Article in journal (Refereed)
    Abstract [en]

    Low-to-medium density chalk can be de-structured to soft putty by high-pressure compression, dynamic impact or large-strain repetitive shearing. These process all occur during pile driving and affect subsequent static and cyclic load-carrying capacities. This paper reports undrained triaxial experiments on de-structured chalk, which shows distinctly time-dependent behaviour as well as highly non-linear stiffness, well-defined phase transformation (PT) and stable ultimate critical states under monotonic loading. Its response to high-level undrained cyclic loading invokes both contractive and dilative phases that lead to pore pressure build-up, leftward effective stress path drift, permanent strain accumulation, cyclic stiffness losses and increasing damping ratios that resemble those of silts. These outcomes are relatively insensitive to consolidation pressures and are distinctly different to those of the parent intact chalk. The maximum number of cycles that can be sustained under given combinations of mean and cyclic stresses are expressed in an interactive stress diagram which also identifies conditions under which cycling has no deleterious effect. Empirical correlations are proposed to predict the number of cycles to failure and mean effective stress drift trends under the most critical cyclic conditions. Specimens that survive long-term cycling present higher post-cyclic stiffnesses and shear strengths than equivalent 'virgin' specimens.

  • 16.
    Liu, Tingfa
    et al.
    University of Bristol, Department of Civil Engineering, Bristol, United Kingdom.
    Ahmadi-Naghadeh, Reza
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Vinck, Ken
    Imperial College London, Department of Civil and Environmental Engineering, London, United Kingdom.
    Jardine, Richard J.
    Imperial College London, Department of Civil and Environmental Engineering, London, United Kingdom.
    Kontoe, Stavroula
    Imperial College London, Department of Civil and Environmental Engineering, London, United Kingdom; University of Patras, Department of Civil Engineering, Patras, Greece.
    Buckley, Róisín M.
    University of Glasgow, School of Engineering, Glasgow, United Kingdom.
    Byrne, Byron W.
    University of Oxford, Department of Engineering Science, Oxford, United Kingdom.
    McAdam, Ross A.
    Ørsted Power (UK) Ltd, London, United Kingdom.
    Laboratory investigation of the cyclic loading behaviour of intact and de-structured chalk2023In: Proceedings of the 8th International Symposium on Deformation Characteristics of Geomaterials (IS-PORTO 2023) / [ed] António Viana da Fonseca & Cristiana Ferreira, 2023Conference paper (Refereed)
    Abstract [en]

    Chalk is a soft biomicrite composed of silt-sized crushable CaCO3 aggregates. Chalk’s response to cyclic loading depends critically on its sensitive micro fabric and state, which may be altered significantly by high-pressure compression, dynamic impact or prior large-strain repetitive shearing. This paper reports high-resolution undrained cyclic triaxial experiments on low- to medium-density intact chalk and chalk de-structured by dynamic compaction to model the effects of percussive pile driving. The intact chalk manifested stable and nearly linear visco-elastic response under a wide range of the one-way, stress-controlled cyclic loading conditions imposed. However, high level cycling led to sudden failures that resembled the fatigue response of metals, concretes and rocks, with little sign of cyclic damage before sharp pore pressure reductions, non-uniform displacements and finally brittle collapses. However, the de-structured chalk’s response to high-level undrained cycling resembles that of silts, developing both contractive and dilative phases that led to pore pressure build-up, leftward effective stress-path drift, permanent strain accumulation, cyclic stiffness losses and increasing damping ratios. Results from exemplar tests are presented to illustrate these key features and demonstrate how chalk’s undrained cyclic shearing characteristics depend also on effective stress level. The experimental outcomes provide significant scope for developing constitutive and empirical relationships or predictive tools to enable the interpretation and design of driven pile foundations in chalk and other chalk-structure interaction related problems under cyclic loading. 

  • 17.
    Liu, Tingfa
    et al.
    University of Bristol, Bristol, UK.
    Jardine, Richard
    Imperial College London, London, UK.
    Vinck, Ken
    Imperial College London, London, UK.
    Ahmadi-Naghadeh, Reza
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Kontoe, Stavroula
    University of Patras, Patras, Greece.
    Buckley, Róisín M.
    University of Glasgow, Glasgow, UK.
    Byrne, Byron W.
    University of Oxford, Oxford, UK.
    Mcadam, Ross A.
    Ørsted Power Ltd, London, UK.
    Cyclic Characterisation of Low-to-Medium Density Chalk for Offshore Driven Pile Design2023Conference paper (Refereed)
    Abstract [en]

    Project-specific advanced laboratory testing is employed increasingly frequently in site investigations for major offshore projects. Such testing needs to focus on characterising properties under in-situ conditions, while also catering for the effects of foundation installation and subsequent service conditions, including cyclic loading. Low-to-medium density chalk, a variable soft biomicrite, can be de-structured to soft paste under dynamic percussion or large-strain repetitive shearing, posing significant challenges and uncertainties for driven pile design. This paper draws on key outcomes from undrained cyclic triaxial test programmes on both intact chalk and dynamically de-structured (putty) chalk. The cyclic response of intact chalk resembles the fatigue behaviour of hard rocks and develops little sign of damage before sharp pore pressure reductions and brittle collapse occurs. In contrast, fully de-structured chalk develops both contractive and dilative phases, as seen with silts. The associated effective stress reductions vary systematically with the number of cycles and cyclic stress ratio. A laboratory-based global axial cyclic predictive method is proposed from the experiments and employed to predict the outcomes of field axial cyclic loading pile tests. The research provides then basis for robust cyclic design guidance for piles driven in low-to-medium density chalk.

  • 18.
    Maghsoudloo, Arash
    et al.
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Ahmadi-Naghadeh, Reza
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Toker, Nabi Kartal
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Numerical Comparison of Retaining System Behavior for a Deep Excavation Case with and Without Ground Improvement2012In: Proceedings of the International Conference on Ground Improvement & Ground Control: 30 October – 2 November 2012, Wollongong, Australia / [ed] Buddhima Indraratna, Cholachat Rujikiatkamjorn & Jayan Vinod, Research Publishing Services, 2012Conference paper (Refereed)
    Abstract [en]

    In the construction of deep excavations in urban areas, the safety of adjacent ground and structures becomes major concern for engineers. In soft clays, the main reason for occurrence of large deflections of soil support systems in excavations is instability of the excavation base. This paper will focus on analyzing and comparing design of an excavation with and without jet grout improvement applied to the excavation base by employing the finite-element code PLAXIS. A well-documented case study is analyzed, and soil properties in the model are calibrated using available field data from inclinometers. Then the same analysis is repeated for the improved case and results are compared. The results reveal the effectiveness of jet grout blocks in decreasing lateral wall movement, base heave and surface settlement on the retained side.

  • 19.
    Olsson, Wilma
    et al.
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Linus, Hansson
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Hållbar masshantering med fokus på massbalans och avfall2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduction (and purpose): At every construction project there is a lot of soil moved around and managed. Mass management is an important topic which affect every project. Mass balance is what is tried to achieve. If mass balance is achieved no masses is bought or transferred from the project. If a project has deficit mass, they need to buy soil from outside of the project and move it with trucks. These transports are usually quite long which means it gets cost inefficient. It also has a negative impact on the climate. If there is excess mass within the project soil needs to be removed with trucks.

    Municipality sees on contaminated soil in different ways depending on where in Sweden it is placed. This can also affect the length on transports of soil.The purpose of the report is to find a solution of how construction company can do mass management together to find mass balance from a bigger perspective instead of the specific project.

    Method: The study will be of a qualitative character and been executed with semi- structured interviews and literature search to answer the studies questions. The interviews have been implemented with land contractors in Jönköping.

    Results and analysis: The study shows that there is some lack in the regulation regarding secondary masses. All municipalities have their own regulation which means that there are different problems depending on where you are located. It takes a long process to reuse masses today which not is economically favorable. The study highlight deficiency that exists today and show suggestions for a more effective mass management. Study shows also that there is an interest for a collective platform where you can buy and sell secondary masses. In that way companies and municipalities can cooperate for a mutual mass management by buying and selling masses from each other.

    Discussion: Through interviews with contractors in the industry the questioning has been confirmed. The result is based on solution and suggestions which can promote a circular mass management. To answer the questions the study is based on different impression, opinions and aspects.

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  • 20.
    Rezaei, Mohammad Mostafa
    et al.
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Husseini, Bahram
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Hinder och drivkrafter för BIM-användning inom kommunens tekniska förvaltning2023Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The construction industry is in great need of digitalization in order toenhance efficiency and conserve resources. To address this need, a system that caneffectively manage information across all stakeholders is necessary. BuildingInformation Modelling (BIM) emerges as a highly promising tool within the industry.However, there are both driving forces and obstacles influencing the adoption of BIMin technical management. This study aims to investigate the utilization of BIM intechnical administration, as well as the obstacles and driving forces impacting itsimplementation. Additionally, the study seeks to identify challenges that can beresolved through the application of BIM.

  • 21.
    Tahershamsi, H.
    et al.
    Chalmers University of Technology, Department of Architecture and Civil Engineering, SE-41296 Gothenburg, Sweden.
    Ahmadi-Naghadeh, Reza
    Jönköping University, School of Engineering, JTH, Construction Engineering and Lighting Science.
    Zuada Coelho, B.
    Deltares, Department of Geo-engineering, MH Delft, 2600, Netherlands.
    Dijkstra, J.
    Chalmers University of Technology, Department of Architecture and Civil Engineering, SE-41296 Gothenburg, Sweden.
    Low amplitude strain accumulation model for natural soft clays below railways2023In: Transportation Geotechnics, ISSN 2214-3912, Vol. 42, article id 101011Article in journal (Refereed)
    Abstract [en]

    An improved constitutive model for strain accumulation of natural clays under undrained cyclic loading is presented. The proposed model includes a formulation for the non-linear small-strain stiffness in the overconsolidated regime, along with a modified hardening law for cyclic accumulation to improve the tracking of strain accumulation at small stress amplitudes. To calibrate and validate the proposed model, a series of laboratory tests were conducted to study the cyclic response of natural Swedish clays, the effect of loading amplitude and pre-shearing history. Good agreement between predicted and measured accumulated axial strains and excess pore water pressures was obtained with different loading amplitudes. The findings reveal that the undrained pre-shearing has a substantial impact on the rate of accumulated strain, with pre-sheared samples exhibiting lower resistance values. The proposed and validated model opens up possibilities to study the monotonic and non-monotonic quasi-static response of soft clays below railway embankments over the lifetime of the structure, i.e. including the effects of construction, operation and decommissioning.

  • 22.
    Tengelin, Elin
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Vetterlund-Handberg, Martina
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    ÅTERANVÄNDNING AV SCHAKTMASSOR2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syfte: Återanvändningen av schaktmassor inom anläggningsbranschen är i dagsläget begränsad. Bland annat på grund av otydliga regelverk samt låga kostnader och hög tillgänglighet av jungfruliga material. Trots att schaktmassor har en hög potential att återanvändas finns det andra alternativ för överskottsmassor som uppstår i ett projekt som är mer fördelaktiga för entreprenörer. Svårigheterna kring återanvändning av schaktmassor är det som skall undersökas och målet med rapporten är följaktligen att undersöka möjligheterna att främja återanvändning av schaktmassor inom anläggningsbranschen. Målet kommer att besvaras med hjälp av två frågeställningar: (1) Hur kan återanvändningen av schaktmassor främjas inom anläggningsbranschen? (2) Hur kan en återanvändningsterminal öka återanvändningen av schaktmassor?

    Metod: Metoderna som valts för att samla empiri till studien är litteraturstudie, dokumentanalys och intervjuer. Litteraturstudien och dokumentanalysen skapade en kunskapsuppbyggnad inom ämnet som bland annat låg till grund för utformningen av intervjuerna. Intervjuerna har genomförts tillsammans med tio respondenter från åtta olika företag inom anläggningsbranschen.

    Resultat: De regelverk och lagar som finns kring hanteringen av schaktmassor ses som det största hindret för återanvändningsmöjligheterna. Svårigheterna att få ekonomisk vinst i återanvändningsprocessen samt långa transporter är också bidragande orsaker. Även de geotekniska egenskaperna på schaktmassornas kan vara problematiskt, dels för att massorna skall klassificeras enligt sin byggbarhet samt att de skall vara jämförbara med jungfruligt material.

    Konsekvenser: Slutsatserna som dragits utifrån studien är att det krävs ett ökat samarbete inom branschen för att återanvändningen av schaktmassor skall främjas. Tydligare kommunikation behövs samt att planering kring masshanteringen bör ske i ett tidigare skeden i projekten. De regelverk och riktlinjer som finns idag behöver omarbetas för att bli tydligare och möjliggöra för ökad återanvändning. En återanvändningsterminal av storskalig verksamhet som placeras centralt skulle bidra till att återanvändningen av schaktmassor ökar vilket minskar miljöpåverkan och gynnar branschen.

    Begränsningar: Studien är begränsad och utförd inom Jönköpings län och intervjurespondenterna är valda utefter de verksamheter som verkar inom länet. Arbetets generaliserbarhet begränsar sig till Sverige eftersom att regelverk och tillvägagångssätt gällande hantering av schaktmassor ser olika ut i andra länder.

    Nyckelord: Utgrävd mark, återanvändning av schaktmassor, återanvändningsterminal, återanvändning av bergmaterial.

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  • 23.
    Vinck, Ken
    et al.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Liu, Tingfa
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Jardine, Richard J.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Kontoe, Stavroula
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    Ahmadi-Naghadeh, Reza
    Jönköping University, School of Engineering, JTH, Civil Engineering and Lighting Science.
    Buckley, Róisín M.
    School of Engineering, Oakfield Ave, Glasgow, United Kingdom.
    Byrne, Byron W.
    Department of Engineering Science, Oxford University, Oxford, United Kingdom.
    Lawrence, James A.
    Department of Civil and Environmental Engineering, Imperial College London, London, United Kingdom.
    McAdam, Ross A.
    Department of Engineering Science, Oxford University, Oxford, United Kingdom.
    Schranz, Fabian
    Department of Engineering Science, Oxford University, Oxford, United Kingdom.
    Advanced in-situ and laboratory characterisation of the ALPACA chalk research site2022In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656Article in journal (Refereed)
    Abstract [en]

    Low-to-medium density chalk at St Nicholas at Wade, UK, is characterised by intensive testing to inform the interpretation of axial and lateral tests on driven piles. The chalk de-structures when taken to large strains, especially under dynamic loading, leading to remarkably high pore pressures beneath penetrating CPT and driven pile tips, weak putty annuli around their shafts and degraded responses in full-displacement pressuremeter tests. Laboratory tests on carefully formed specimens explore the chalk’s unstable structure and markedly time and rate-dependent mechanical behaviour. A clear hierarchy is found between profiles of peak strength with depth of Brazilian tension (BT), drained and undrained triaxial and direct simple shear (DSS) tests conducted from in-situ stress conditions. Highly instrumented triaxial tests reveal the chalk’s unusual effective stress paths, markedly brittle failure behaviour from small strains and the effects of consolidating to higher than in-situ stresses. The chalk’s mainly sub-vertical jointing and micro-fissuring leads to properties depending on specimen scale, with in-situ mass stiffnesses falling significantly below high-quality laboratory measurements and vertical Young’s moduli exceeding horizontal stiffnesses. While compressive strength and stiffness appear relatively insensitive to effective stress levels, consolidation to higher pressures closes micro-fissures, increases stiffness and reduces anisotropy.

  • 24.
    Wetterheim, Hanna
    et al.
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Josefsson, Hiba
    Jönköping University, School of Engineering, JTH, Civil Engineering.
    Sulfidjord – En analys av förbelastning och vertikaldränering med förbelastning2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med detta examensarbete är att undersöka två olika grundförstärkningsmetoder på sulfidjord, vertikaldränering med förbelastning samt förbelastning, och komma fram till vilken metod som är lämpligast med avseende på sättningar, portryck och hållfasthet. Anledningen till detta arbete är att sulfidjord har dålig bärighet och är sättningsbenägen, vilket gör det till en nödvändighet att förstärka jorden innan byggnation. Sulfidjord har dålig miljöpåverkan vid kontakt med syre och ska inte grävas upp. Därför är de två förbelastningsmetoderna bra att använda på denna typ av jord. I Sverige finns jorden främst längs Norrlandskusten, vilket är det område som rapportens undersökningar kommer från.Datainsamlingsmetoderna som legat till grund för arbetet har huvudsakligen samlats in genom kvalitativa insamlingsmetoder i form av litteraturstudier av tidigare forskningsarbeten samt intervju med sakkunnig geotekniker. Genom dokumentanalys har kvantitativ insamlingsmetod använts, då insamling av mätvärden från undersökningar genomförts för att ta fram ett resultat.Resultatet sammanställdes och visade att vertikaldränering med förbelastning är en mer optimal förstärkningsmetod att utgå från, utifrån de faktorer som har undersökts. Vid vertikaldränering med förbelastning går tidsförloppet fortare för sättningar och protrycksutjämning. De olika försöken har sammanställts i tabell och ett resultat kunde fås.De skrivna frågeställningarna som behandlades och besvarades i rapporten visade på att vertikaldränering har en snabbare inverkan. Tid kan sparas om metoden väljs och byggnation kan därefter göras på den styvare jorden. Denna rapport har begränsats då den bara behandlar två specifika förstärkningsmetoder. Ekonomiska aspekter och miljöpåverkan tas inte med i rapporten för att inte riskera att ämnet blir stort. Nyckelord: förbelastning, förstärkningsmetoder, sulfidjord, vertikaldränering och överlast.

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